题目

据考古发现，商周时期的青铜器多为礼器和兵器，北方出土的青铜农具比江淮出土的青铜农具要少。导致这一状况的原因应该是（） A . 商周的青铜冶铸业水平不高 B . 商朝的统治者对农业生产不重视 C . 北方统治者重礼制和军事 D . 江淮地区富含铜、锡、铅矿 答案：C—Tom is never late for work. Why is he absent today?   —Something _____ to him. [     ]A. must happen                B. should have happened  C. could have happened          D. must have happened